[Teflon spacer replacement]

Also not having a spring can cause issues. The material wants to slightly expand when heated. If it doesn't have space to expand linearly it could possibly effect the diametrical clearance. It is small amounts but could have an effect

 

Good point!

Then I may have to drill the PTFE a little as a buffer.. I will also diminish the temperature a little and put a 5 cfm fan as a replacement.

[Teflon spacer replacement]

260c... Maxed out. You are reducing friction with heat, yes but there are other material issues!. This temperature is where the ptfe will start to break down. This may make things worse over time.

I'd order a new one and then

Since you cut it. Maybe Try re drilling out the hole slightly making sure it is clean inside and all edges are smooth. Slide the filament before and after, you should notice a drastic improvement with friction.

Also

Have you modified the feeder yet?

Print Irobertls feeder it allows you to Better adjust the pressure on the filament. Make sure you make all the parts where the filament can touch smooth. also ensure your Bowden tube is secure and not moving with the retraction.

 

Yep I have Robert's feeder. It's one of the first thing I've done. My ABS filament roll is also on the floor in straight line with the feeder input. So there's no friction there. I know when a problem occur, because I see that the feeder gear will get ABS dust on it, but that only happened before my modification. The feeder stepper no longer skip backs now.

I didn't drill out the spacers, but they don't seem to have that much friction, I can slide the filament in them and extrusion is easy. I may drill them out if I sense they are causing too much problem over time!

I certainly don't like extruding at 260.. With my TOM I was extruding at 225-230 and never had problems..

I am beginning to wonder if my real problem is the thermocouple, maybe it is reporting a higher temperature?

My problem seems to be that during retraction, the filament comes back in the spacer and in fact it stretches instead of being pulled up. So there's a little plastic left in the tip, when the filament pushes back after retraction, that's when I have problems (at 240). Like if the filament wasn't able to heat back instantly to melt. There's a delay there that will cause heavy under extrusion for some time. The only thing I can think of, is insufficient temperature at this point.. Unless I am misunderstanding the issue...

I feel that at 240 it should be more than enough to print ABS, but at 260 there's a BIG improvement in quality and layer bonding!

 

[Teflon spacer replacement]

Ok it looks like it didn't work..

At 240 it didn't work, at 260 it does work, and it does print VERY GOOD!

Ok I might trigger the gun too fast here, but the ultimaker robot passed the retraction layers and it's the most beautiful I printed as of yet; and it's printed in ABS..

Let's see how this goes...

** Best robot I have to date while printing ABS. I guess 260 degrees helped a lot to reduce the forces needed to push the filament and retract.

 

[Teflon spacer replacement]

I am currently trying a little hack I made to the hotend..

 

I cut off a portion of the PFTE white spacer and reversed it, put it on the top aluminum plate, I then inserted the PFTE red tube that came with my thing-o-matic MK6 head in the white spacer and cut it so it's flush with the hotend.

 

It seems to work pretty well for now, I didn't do any exhaustive printing with it yet, but at least it works and retraction works too!

 

The red PTFE tube of the thing-o-matic is more slippery and seems more durable than the PTFE white spacer of ultimaker.. I don't know why tho.. But it served me well in my TOM and it endured 3 years of non-stop printing..

*And I also removed the spring since it became obsolete...

** And I've put thermal paste on the aluminum heatsink where it contacts the plates

 

[Teflon spacer replacement]

Update, I wanted to see if I could fix the PTFE design.

I acquired some high quality PTFE bar stock (we have as leftovers at work). I made some small changes to the design of the original spacer.

Added a 0.5 mm chamfer to the opening to allow for easier entrance and for retraction, also increased the hole size to 3.97. Rounded the exit area slightly. I tested this first had no issues.noticed a drastic improvement similar to my peek one.

After this test I modified the original PTFE part to match; instant improvement also.

 

I'm still interested in buying one of your PEEK spacer

With the bigger hole, wouldn't your filament hit the metal hot end flat part when retracting too far and going back in the metal tip from the PTFE spacer ? I do understand tho that the filament would be thinner at the tip, thus it might be "self-centering" ..

I received a diamond blade I ordered. I will improvise and try to machine a ceramic rod in a spacer. I will try with a larger hole, as you did, maybe this will prevent the PLA from glueing to the ceramic spacer.. Or else, I will try to create a spacer in which the PTFE spacer will sit..

 

[Teflon spacer replacement]

I have one of the first versions of the U2, and I have been having issues with printing under extrusion. I so far have been able to correct this by simply printing a bit slower. I was meaning to order a new one and or call ultimaker to have one shipped.

One issue with the PTFE is its compressive and tensile strength, especially near heat.

I have access to a lot of scrap peek, so I decided to create a PEEK replacement.

The comparisons are as follows:

Tensile Strength: PTFE = 25-35MPa, Peek = 90-100MPa

Compressive Strength PTFE = 30-40MPa, Peek 140MPa

Thermal expansion is approx 1/3 lower for Peek.

The machine ability of PEEK is better than PTFE and it is easier to have a smoother polished surface.

With the constant movement of the filament wire through the PTFE the higher strength PEEK should maintain its structure better than the PTFE allowing it to avoid possible friction issues.

I conducted the flow test cyclinder to 10mm3/s and noticed an improvement of two levels. I was able to complete the cyclinder with the new PEEK spacer.

 

Do you sell those? I'd like to buy one

 

[Teflon spacer replacement]

Ultimaker support sent me a new spacer, very efficient customer support! I will buy ESC fans and try to increase airflow and also reduce spring pressure. Thanks for the suggestions!

 

[Teflon spacer replacement]

I don't have experience on ceramic replacement, but I have seen Ultimaker employees writing that PLA sticks to ceramic materials _very_ efficiently. Besides friction, I would be concerned about tightness of the fit between (ceramic) isolator and the actual nozzle unit. As PTFE is slightly elastic, it makes a tight fit with the nozzle unit.

My solution was to improve airflow towards the Teflon isolator:

http://umforum.ultimaker.com/index.php?/topic/6307-um2-twin-tornadoes/

It helped a lot. As I have also built a closed chamber for my UM2, my need for cooling the PTFE isolator was accented.

 

This is impressive! I will add more airflow to the isolator as well, I'm sure it will help, since I also print mainly in ABS.

 

Stainless steel would be good as it's not very heat conductive.

UM has a "new" glass infused teflon isolator but if you got the printer less than 3 months ago (you said 2 months) then I suspect you might already have it.

 

I do have a recent printer, I'm not sure how to identify that my teflon part is the new material or not, but it's all brown and scored inside.. I'm not sure what happened exactly, maybe it did sit down a long time while heating the heatbed with the head at operating temperature.. I will probably need to preheat the head bed first, but in the end, I feel that the teflon part must go and be replaced with something better. I'm open to new materials!

One thing is sure, I'm going to add airflow to this part!

 

[Teflon spacer replacement]

First post, so a little background first:

I am quite new with the ultimaker 2, I had it for 2 months now. I do have a lot of experience with the makerbot thing-o-matic.

Ok, so my teflon spacer scored from the inside and is brown from burning in the hot end. I did print with the provided PLA roll at first but switched to ABS right after that and printed some ninja flex in between.

My hot end was at 240 celsius and I use the Robert's feeder since the original one wasn't up to the task with ninja flex.

Everything was fine for a while, really didn't have any major problems, but then with retraction, the hot end would jam up.. So there are some deep grooves and scoring marks in the teflon part.

I submitted a ticket, and ultimaker replied quite fast.. I don't know yet if they will send me a replacement teflon spacer, but I believe I will have more problems with it in the end..

SO, I was wondering if someone made a ceramic replacement Spacer? I was going to try and make one, but machining ceramic on the cheap is going to be quite challenging I fear!

I know there is the e3d all metal hot end, from my quick search on the forums, it looks like it would be a great replacement .. However, I do feel a bit foolish to have put all that money in a printer and change everything after 2 months!

With my thing-o-matic, I NEVER had to disassemble the hot end and it definitely NEVER jammed up on me.. I'd like my ultimaker2 to have that same reliability